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+/* ===========================================================
+ * docsify sw.js
+ * ===========================================================
+ * Copyright 2016 @huxpro
+ * Licensed under Apache 2.0
+ * Register service worker.
+ * ========================================================== */
+
+const RUNTIME = 'docsify'
+const HOSTNAME_WHITELIST = [
+ self.location.hostname,
+ 'fonts.gstatic.com',
+ 'fonts.googleapis.com',
+ 'unpkg.com'
+]
+
+// The Util Function to hack URLs of intercepted requests
+const getFixedUrl = (req) => {
+ var now = Date.now()
+ var url = new URL(req.url)
+
+ // 1. fixed http URL
+ // Just keep syncing with location.protocol
+ // fetch(httpURL) belongs to active mixed content.
+ // And fetch(httpRequest) is not supported yet.
+ url.protocol = self.location.protocol
+
+ // 2. add query for caching-busting.
+ // Github Pages served with Cache-Control: max-age=600
+ // max-age on mutable content is error-prone, with SW life of bugs can even extend.
+ // Until cache mode of Fetch API landed, we have to workaround cache-busting with query string.
+ // Cache-Control-Bug: https://bugs.chromium.org/p/chromium/issues/detail?id=453190
+ if (url.hostname === self.location.hostname) {
+ url.search += (url.search ? '&' : '?') + 'cache-bust=' + now
+ }
+ return url.href
+}
+
+/**
+ * @Lifecycle Activate
+ * New one activated when old isnt being used.
+ *
+ * waitUntil(): activating ====> activated
+ */
+self.addEventListener('activate', event => {
+ event.waitUntil(self.clients.claim())
+})
+
+/**
+ * @Functional Fetch
+ * All network requests are being intercepted here.
+ *
+ * void respondWith(Promise<Response> r)
+ */
+self.addEventListener('fetch', event => {
+ // Skip some of cross-origin requests, like those for Google Analytics.
+ if (HOSTNAME_WHITELIST.indexOf(new URL(event.request.url).hostname) > -1) {
+ // Stale-while-revalidate
+ // similar to HTTP's stale-while-revalidate: https://www.mnot.net/blog/2007/12/12/stale
+ // Upgrade from Jake's to Surma's: https://gist.github.com/surma/eb441223daaedf880801ad80006389f1
+ const cached = caches.match(event.request)
+ const fixedUrl = getFixedUrl(event.request)
+ const fetched = fetch(fixedUrl, { cache: 'no-store' })
+ const fetchedCopy = fetched.then(resp => resp.clone())
+
+ // Call respondWith() with whatever we get first.
+ // If the fetch fails (e.g disconnected), wait for the cache.
+ // If there’s nothing in cache, wait for the fetch.
+ // If neither yields a response, return offline pages.
+ event.respondWith(
+ Promise.race([fetched.catch(_ => cached), cached])
+ .then(resp => resp || fetched)
+ .catch(_ => { /* eat any errors */ })
+ )
+
+ // Update the cache with the version we fetched (only for ok status)
+ event.waitUntil(
+ Promise.all([fetchedCopy, caches.open(RUNTIME)])
+ .then(([response, cache]) => response.ok && cache.put(event.request, response))
+ .catch(_ => { /* eat any errors */ })
+ )
+ }
+})